So I was pondering a question this morning during my study of Acts 6: Why were 7 men chosen to serve tables -- not fewer and not more? Some say it was because of the reverence for the number 7 among the Jews. Other answers are more esoteric. But see Lightfoot below:
His comment hits a home run. If you've ever studied Latin, you can probable figure it out. The main challenge for most people is probably going be the verb dicat. This is the third singular of dicere, "to say." But how should we translate it? Here's a clue, based on the third singular of the various forms of dicere:
Indicative = dicit ("he says")
Imperfect = dicebat ("he was saying")
Future = dicet ("he will say")
Perfect = dixit ("he has said")
Pluperfect = dixerat ("he had said")
AND FINALLY ...
Subjunctive = dicat ("let him say")
Thus, I would render "quare septem eligendi, dicat cui est audacia" as follows:
"As to why seven were chosen, let him say who has the audacity."
In other words, your guess is as good as mine!
In the end, Barnes is probably correct is saying that 7 was a commonsense number -- "sufficiently large to secure the faithful performance of the duty, and not so large as to cause confusion and embarrassment."
So there you have it -- why there were 7.